Investigation on utilization of polyethylene terephthalate (PET) in the production of eco-friendly concrete: experimental, statistical and life cycle assessment

Generation of waste from industries pollutes the environment. The concern arises from the difficulty in recycling and reuse of waste in terms of process and cost. One such important waste that needs consistent management through recycling and reuse is plastics which contributes to higher environmental impact. The conventional disposal techniques results in land depletion and pollution, while the construction sector is seeking suitable substitute to river sand owing to its depletion. This study investigates the efficacy of Polyethylene terephthalate (PET) bottles as a fractional substitute for fine aggregates in the production of sustainable concrete. The PET was incorporated at various levels of 5%, 10%, 15%, 20%, 25%, and 30% by weight of fine aggregate. The workability of PET was lowered by 49% at 30% and the water absorption of PET concrete was 61% higher. The optimal substitution was observed at 10% showing only 1.96% lower strength than control concrete. At higher proportions, the flexural and tensile strength was 24% and 22% lesser and elastic modulus was 15% lower. Microstructural investigations performed through Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) validate the presence of pore volume in the mixes with PET aggregates. Life cycle assessment (LCA) with openLCA software show 18.82% lower global warming potential (GWP), 7.30% lesser embodied energy and 15% lower water use. Life cycle cost analysis (LCCA) shows upto 8% cost-cutting with 10% of PET. Response surface methodology (RSM) was used to optimize the mix design, attaining 0.87 desirability with balanced hardened, economic and environmental objectives.